Well completion apparatus



July 30, 1968 w. M. TERRY WELL COMPLETION APPARATUS Filed Feb. 15, 1967 WILLIAM M. TERRY INVENTOR.

BY gw.) i. QML

ATTORNEY United States Patent O 3,394,767 WELL COMPLETION APPARATUS William M. Terry, Houston, Tex., assignor to Esso Production Research Company, a corporation of Delaware Filed Feb. 13, 1967, Ser. No. 615,549 8 Claims. (Cl. 175-4.52)

ABSTRACT F THE DISCLOSURE A tool for perforating a well and injecting fluid into the surrounding formation which includes a rigid upper section containing the perforator and means for directing fluid into the perforation and a flexible lower section in which at least part of the uid is held prior to injection.

Background of the invention (1) Field of the invention-This invention relates to tools for use in the completion of oil and gas wells and is particularly concerned with a completion tool for perforating a pipe string and injecting uid into the surrounding subsurface formation.

(2) Description of the prior arzt-The widespread use of plastics and resins for the consolidation of incompetent formations surrounding oil and gas wells has lead to the development of shoot-and-inject tools provided with means for perforating a pipe string and injecting fluid into the perforated zone. One such tool is described in U.S. Patent 3,153,449. Although tools of this type have been widely used, experience has shown that those available heretofore have certain limitations. Because of the substantial quantities of plastic, catalyst, flushing agent and other fluids generally required, the conventional shootand-inject tools are too large for small diameter pipe strings in deviated wells. This restricts their use, particularly in offshore operations where many deviated wells containing small diameter strings may be drilled from a single platform.

Summary of the invention The improved completion tool of this invention is provided with a rigid upper section including means for perforating an isolated section of a pipe string and directing fluid into the perforation and an elongated flexible lower section containing a reservoir in which at least part of the uid is held prior to the injection step. The upper section of the tool may be of conventional design but will preferably be of somewhat smaller diameter. The flexible lower section provides the fluid capacity required for sand consolidation and similar operations and yet permits passage of the tool through small diameter pipe strings in deviated wells without difliculty. This facilitates the completion of wells in which tools available heretofore cannot be used and hence the improved tool has advantages over equipment of the prior art.

Brief description of the drawing FIGURE 1 in the drawing is a vertical section through a wellbore containing a completion tool provided with a rigid upper section including means for Perforating and injecting fluids and an elongated flexible lower section containing a reservoir in which at least a portion of the fluid is held prior to injection. FIGURE 2 is a fragmentary section through the lower portions of an alternate embodiment of the invention. FIGURE 3 depicts the fiexible lower section of another alternate embodiment.

Description 0f the preferred embodiments FIGURE 1 in the drawing depicts a well-bore which has been drilled from the earths surface through subsurface formation 11 and is provided with casing 12 surrounded 3,394,767 Patented July 30, 1968 ACC by cement sheath 13. Completion uid 14 stands in the wellbore. The hydrostatic pressure exerted by the completion fiuid exceeds the expected formation pressure so that fluids in the formation can be controlled. A well completion tool 15 is suspended in the wellbore by means of electric cable 16. The completion tool includes a rigid upper section 17 provided with a shoe 18 for forcing the tool laterally against the wellbore wall. The shoe is connected to piston rods 19 which in turn are attached to pistons 20. The pistons are housed in hydraulic cylinders 21 and are held in a normally retracted position by means of coil springs 22. The cylinders are connected by passageways, only one of which is shown, to a hydraulic actuating system 23 of the type shown in U.S. Patent 2,674,213 or to other conventional hydraulic actuating means.

The upper section of the apparatus of FIGURE 1 is also provided with a chamber 24 in which a jet perforator 25, shown by dotted lines, is located. The perforator will normally be a conventional shaped charge. As the apparatus is depicted in FIGURE 1, the perforator has been fired to rupture a thin walled section in the chamber Wall and perforate casing 12 and cement 13, The perforation is indicated by reference numeral 26. Annular sealing member 27 mounted on the outer surface of the tool surrounding the thin walled section prevents the entry of the wellbore uid into the perforation and chamber 24. The perforator, firing mechanism, and associated equipment employed in the upper section of the apparatus may be of the type described in U.S. Patent 3,153,449 and hence need not be described in detail. More than one such perforator may be provided if desired.

Chambers 28 and 29 are located below chamber 24 in the upper section of the tool shown in FIGURE 1. Chamber 28 communicates with chamber 24 through passageway 30 containing valve 31. The valve may be of the type described in the aforementioned U.S. Patent 3,153,- 449. This type of valve is opened by an explosive charge detonated by an electrical connection to a surface power supply. Other valves operated 'by solenoids or similar devices may be utilized in place of the explosively actuated valve if desired. Chambers 2S and 29 are separated by a piston 32 containing a valve 33. The valve is held in a normally closed position by the fluid beneath the piston and is opened when the valve reaches the upper end of chamber 28. Piston 34 containing a similar valve 35 is located near the lower end of the upper section. Valve 35 opens on contact with the underside of valve 33. The valves in pistons 32 and 34 may be dispensed with -by providing an enlarged area below valve 31 of suiiicient diameter to permit uid to bypass the pistons. Once a piston moves into this enlarged area, the fluid beneath it can pass around the piston into passageway 30 and hence valves 33 and 35 are unnecessary.

The flexible lower section of the apparatus of FIGURE 1 includes an elongated sleeve or bellows 36 of corrugated metal, reinforced plastic or similar material. The corrugations extend circumferentially about the sleeve to facilitate lateral bending. A shoe 37 containing Huid entry port 3S is attached to the lower end of sleeve 36. A tubular inner liner 39 of rubber, polyethylene or similar pliable material is affixed to the upper end of sleeve 36 and extends downwardly within the sleeve. At the lower end of the liner is a loose-fitting piston 40 of rubber, plastic or similar material sufficiently small to move through the corrugated sleeve without diiculty. This piston seals the lower end of the pliable liner and prevents contamination of the fluid contained therein by wellbore fluid entering the tool through port 38. The liner conforms to the Wall of the corrugated sleeve above the piston due to pressure exerted by the fluid contained therein and below the piston acts as a rolling seal diaphragm as the piston moves upwardly within the sleeve. Two or more such pliable liners and loose-fitting pistons may be provided if more than one fluid is to be contained in the flexible section of the tool. It will also be apparent that the entire lower section need not be made of flexible material and that an articulated structure made up of short rigid tubes interconnected by bellows or the like to give the necessary overall flexibility may be employed if desired.

FIGURE 2 of the drawing depicts an alternate embodiment of the invention. The rigid upper section of the tool shown in FIGURE 2 may be identical to that of the apparatus of FIGURE l. The flexible lower section of the apparatus is an elongated collapsible tube 45 which is bonded or otherwise affixed to the lower end of rigid upper section and is closed at its lower end. The sleeve or tube may be made of rubber, plastic, coated fabric, metallic foil or similar material. The wall thickness decreases from the upper end to the lower end so that the resistance to collapse is less at the bottom of the flexible member than at the top. As a result, hydrostatic pressure outside the apparatus tends to displace fluid from within the tube by progressively collapsing it from bottom to top. It will be apparent that the entire periphery of the tube or sleeve need not be collapsible and that the structure of FIGURE 2 may include one or more longitudinal ribs of metal or similar material which are sufficiently flexible to permit passage of the apparatus through small diameter strings in deviated wells but sufficiently rigid to strengthen and partially support the tube or sleeve.

Still another embodiment of the invention is shown in FIGURE 3 of the drawing. This embodiment differs from those shown in FIGURES l and 2 in that all of the fluid chambers or reservoirs are contained in the flexible lower section of the tool. The upper portion of the rigid section may again be substantially identical to that of the tool shown in FIGURE 1 and will include a piston assembly for forcing the tool against the borehole wall, a perforating gun, means for actuating the piston assembly, an annular sealing member, and a valve 50 for admitting fluid into the upper section from the reservoirs contained in the flexible lower section. The lower section shown includes an elongated flexible tube S1 of rubber, plastic or similar material having smooth inner Walls. Tube 51 is bonded or otherwise connected to the lower end of upper section 15 and is provided with one or more openings 52 at its lower end Ifor admitting wellbore fluid into the device. The fluids in flexible tube 51 are contained in individual bags or containers 53, 54, 55 and 56 of polyethylene or similar plastic film. The film selected should be substantially inert to the fluids which are to be handled. The outer surfaces of the bags may be coated with grease or other lubricating material to reduce friction against the inner wall of tube 51. The lower end of rigid upper section .15 within tube 51 is provided with a sharp, elongated spur or similar means 57 adjacent the pasageway extending to valve 50. As the bags are forced upwardly in the flexible tube by wellbore fluid entering the lower end of the tube through ports 52, each bag in turn is punctured by spur 57, liberating the fluid contained therein. This permits injection of the fluids into the perforation in order with little mixing of fluids in the tool itself.

The tool of this invention may be employed in much the same way that conventional tools are used and hence requires no little or no modification of existing completion and treatment procedures. In a sand consolidation operation carried out with the apparatus of FIGURE l for example, two resin-forming liquids may be placed in chambers 28 and 29 in the upper section of the tool and the oil or other fluid which is to be employed as an afterflush may be placed in the lower section between piston 34 and loose-fitting piston 40. The tool is then lowered in the wellbore to the point adjacent formation 11 where a perforation is required. Shoe 18 is forced against the wellbore wall by actuating pistons 20 within cylinders 21. This forces annular seal 27 against the casing and thus isolates a section of the casing from the high pressure fluid 14 in the wellbore. let perforating gun 25 is actuated to form a perforation 26 extending through casing 12 and cement 13 into formation 11. Fluid entrapped in the isolated area may be permitted to flow into chamber 24 by allowing momentary production from the perforation. Valve 31 is then opened. In response to the differential pressure between the fluid in the wellbore and that it the perforation, wellbore fluid tends to enter port 38 and force loose-hitting piston 40 upwardly within the flexible sleeve. Pistons 32 and 34 move upwardly in the rigid section of the tool. Fluid from upper chamber 28 flows through valve 3.1 and passageway 30 into chamber 24 and perforation 26. When piston 32 reaches the upper end of chamber 28, valve 33 contacts the end of the chamber and opens as the piston continues to move upwardly about it. Fluid from between pistons 32 and 34 then flows through valve 33, displacing fluid from passageway 30 and flowing into the perforation. Pistons 34 and 40 continue to move upwardly as this second fluid is depleted. Sleeve 39 acts as a rolling seal diaphragm, following floating valve 40 at its lower end. After valve 35 contacts valve 33, piston 34 moves ahead a short distance so that the fluid to be used as the afterflush may pass through the openings in pistons 32 and 34. Injection of the afterflush into the perforation continues until the fluid is exhausted or the pressure in the perforation approaches the wellbore pressure. At this point, the operation is complete. Shoe 18 may be retracted and the tool withdrawn from the wellbore. The alternate embodiments shown in FIGURES 2 and 3 may be used in similar manner.

I claim:

1. A tool for perforating a pipe string and injecting a fluid through the perforation into a surrounding subterranean formation which comprises a rigid body section; a sealing member on the outer surface of said rigid body section for isolating an area on the inner wall of said pipe string from fluids in the pipe string; means in said rigid body section for holding said sealing member in contact with said inner wall; perforating means in said rigid body section for forming a perforation in said pipe string within said isolated area; a passageway in said rigid body section for introducing fluid from within said tool into said isolated area; valve means normally closing said passageway; means for opening said valve means after said perforation has been formed; and a laterallyflexible body section attached to said rigid body section, said flexible section containing a chamber communicating with said passageway in said rigid section and including means responsive to fluid pressure in said pipe string for forcing fluid from said chamber through said passageway into said isolated area.

2. A tool as defined by claim 1 wherein said flexible body section comprises a laterally flexible bellows.

3. A tool as defined by claim 1 wherein said means responsive to hydrostatic pressure comprises a pliable tubular liner in said flexible body section and a loosefittcing piston to which said liner is attached near its outer en 4. A tool as defined by claim 1 wherein said rigid body section includes a chamber extending from said passageway to said flexible body section and said chamber contains at least one piston.

5. A tool as defined by claim 1 wherein said flexible body section comprises a collapsible tube connected at one end to said rigid body section and closed at the other end.

6. A tool as defined by claim S wherein the wall of said collapsible tube decreases in thickness in the direction away from said rigid body section.

7. A tool as defined by claim 1 wherein said flexible body section comprises a laterally flexible, smooth-walled tube containing a iluid entry port and said means responsive to hydrostatic pressure comprises at least one pliable fluid-filled container positioned within said tube, said tool including means for puncturing said container within said tube.

8. A tool as defined by claim 7 wherein said means for puncturing said container comprises a sharp, elongated spur extending into said tube from said rigid body section adjacent said pasageway.

References Cited UNITED DAVID H. BROWN,

STATES PATENTS Kisling 166-100 Smink et al. 166-162 Fields 166-100 X Brown 166-100 X Lanmon 166--100 X Primary Examiner. 

